Soluble oil



United. rates Patent SOLUBLE ()IL James L. Jezl, Swarthmore, Pa.,assignor to Sun Oil Company, Philadelphia, Pa., a corporation of NewJersey No Drawing. Application November 13, 1952, Serial No. 320,353

4 Claims. (Cl. 25233.3)

This invention relates to soluble oil compositions comprising mineraloil, alkali metal soap of carboxylic acids obtained by partial oxidationof mineral oil, and an added organic compound.

It is known in the art to prepare soluble oil compositions emulsifiablein water to form oil-in-water emulsions by forming a mixture of mineraloil and alkali metal soap of carboxylic acids obtained by partialoxidation of mineral oil. Such compositions may be called forconvenience synthetic soluble oils to distinguish them from soluble oilcompositions which do not contain soaps of acidic products of oxidationof mineral oil. Major problems involved in the preparation of syntheticsoluble oil compositions have been the obtaining of a stable,homogeneous mixture of oil and soap prior to emulsifioation, and theobtaining of a stable emulsion after emulsification. The presentinvention provides a highly stable, homogeneous mixture of oil and soap,and a highly stable emulsion, these effects being obtained by theincorporation in the soluble oil composition of an organic compound ascoupling agent or mutual solvent, i. e., solvent for both oil and water.The organic compound employed has a. dual function since it bothstabilizes the soluble oil prior to emulsification and stabilizes theemulsion after emulsification.

The compound employed as coupling agent in synthetic soluble oilsaccording to the invention is a primary amyl alcohol. Any of the fourisomeric primary amyl alcohols can be used. Secondary and tertiary amylalcohols, however, are not within the scope of the invention.

The soluble oil composition according to the present invention comprisesmineral oil, alkali metal soap of carboxylic acids obtained by partialoxidation of mineral oil, and an organic compound as specified above. Itis generally preferred that the composition should also contain otherconstituents such as petroleum sulfonates and small amounts of excessalkali metal hydroxide and water. In some cases, it may be desirable toincorporate in the soluble oil, alkali metal soap of petroleumnaphthenic acids. Also, in .some cases, it may be desirable to incorporate in the soluble oil the entire product of oxidation of mineral oil,rather than just a predominantly carboxylic acid portion thereof.

The organic compound employed according to the invention as couplingagent or mutual solvent for synthetic soluble oil's may be used ifdesired in conjunction with other coupling agents or mutual solvents, e.g., monobutyl ether of ethylene glycol. Also, mixtures of two or morecoupling agents according to the present invention may be employed.

Preferably the sulfonate concentration of synthetic soluble oilsaccording to the invention is sufficient to provide a sulfonatesaponification number equivalent of at least 3. Generally, the sulfonatenumber equivalent is not greater than 10, more preferably not greaterthan 7. The sulfonate saponification number equivalent is determined bymeasurement, in mg. of KOH per gram, of the saponification number of thesulfonate-containing material prior to mixing with other saponifiablecomponents of the soluble oil, and multiplying the saponification numberthus obtained by the weight fraction of the sulfonatecontaining materialin the compounded soluble oil.

Preferably, the concentration .of carboxyl-containing materials in thesoluble oils according to the invention is sufficient to provide acarboxylate saponification number equivalent of at least 10, morepreferably at least 14. Generally, the carboxylate saponification numberequiv alent is not greater than 20, more prefer-ably not greater than17. The carboxylate saponification number equivalent may be determinedin a manner generally similar to that described for determination .ofsulfonate saponifi-cation number equivalents.

The synthetic soluble oils according to the invention are preferablyalkaline, having for example free alkalinity within the range 0.01 to0.12 percent as NaOH.

The mineral lubricating oil employed in the soluble oil compositionaccording to the invention preferably has 8. U. viscosity at F. withinthe range from 40 to 120.

The mineral oil' which is used as oxidation charge, on the other hand,preferably has S. U. viscosity at F. within the range froml25 to 200. Apreferred oxidation charge is petroleum foots oil, but minerallubricating oils may also be used. Mineral oil, as the term is used inconnection with the oxidation charge, is understood to include petroleumwax, preferably paraffin wax having melting point not greater than 100F.,. as well as normally liquid oils.

Petroleum foots oil is the oily byproduct obtained in the deoiling ofslack wax. When the deoiling is done by sweating, the foots oil issometimes called sweat oil or sweater oil. When the deoiling is done byfiltration of a solution of the slack wax in a solvent for oil, thefiltrate obtained is a .solution of foots oil in the solvent used, c. g.methyl ethyl ketone or mixtures thereof with toluene and/ or benzene.Petroleum foots oils generally contain substantial amounts oflow-melting wax in addition to lubricating oil, the amount of waxdepending on the filtra' tion temperature and other variables.

The oxidation charge should have sufliciently low coning the heatedcharge oil in liquid state with a f-reeoxygen-containing gas, e. g. air,oxygen, ozonized lair, etc. The oxidation is preferably conducted underatmospheric pressure or relatively low elevated pressure not exceeding,for example, 100 p. s. i. g. Such operation is advantageous in that thevent gases carry off some of the lower-boiling acidic products, whichare undesirable in the soluble oil, and which in operation at higherpressures would remain in the liquid oxidation product. The oxidation ispreferably conducted in the presence of an oxida tion catalyst, such asmanganese naphthenate, manganese soaps of fatty acids, manganese soapsof carboxylic acids obtained in previous oxidations of mineral oil, etc.

The oxidation preferably is continued at least until the saponificationnumber of the liquid oxidation product is 60, and is terminated beforethe saponification number of the liquid oxidation product exceeds 120,preferably before the saponification number exceeds 100. Oxidation totoo high a saponification number tends to result in formation ofoxidation products which have adverse effect on the soluble oil.

A preferred range of coupling agent concentration in the soluble oilaccording to the invention is from 1.75 to 3.0.volume percent. Apreferred range of water concentration in the soluble oil is from 2.75to 5.0 volume percent, more preferably from 2.75 to 3.75 volume percent.Generally, for a given soluble oil there should be at least a certainamount of coupling agent to obtain satisfactory results, but this amountvaries for different properties and relative proportions of the otherconstituents of the soluble oil. Also, there should generally, forsatisfactory results, be a water content within certain upper and lowerlimits, but these limits also vary for different properties and relativeproportions of the other constituents of the soluble oil.

The following examples illustrate the invention:

Example I A synthetic soluble oil was prepared by mixing the followingmaterials in the stated amounts:

Mineral lubricating oil grams 490 Partially oxidized petroleum foots oildo 108 Petroleum naphthenic acids ndo 140 Petroleum mahogany sulfonates(10.9% solution in mineral oil) grams 250 Caustic soda, 50 B milliliters17 adjusting the water content of the soluble oil to 3.5 vol-- umepercent concentration, and adding n-amyl alcohol, CH3(CH2)4OH, ascoupling agent in 2.0 volume percent concentration.

The lubricating oil used had S. U. viscosity at 100 F. of about 100. Thenaphthenic acids had saponification number of 61. The petroleumsulfonates were sodium soaps of sulfonic acids having saponificationnumber of 13.2, and contained 1.80 weight percent organic S03.

The oxidized foots oil was prepared by partially oxidizing a foots oilobtained in the solvent deoiling of slack wax, the oxidation beingper-formed at 260320 F. and atmospheric pressure by blowing air throughthe foots oil containing a manganese-naphthenate containing catalyst.The oxidation was continued until the saponification number of theliquid oxidation product was 78, and 108 grams of that product were thenincorporated in the soluble oil.

The naphthenic acids and oxidized foots oil each contributed 8.5saponification number equivalent to the soluble oils, and the sulfonatescontributed 3.3 saponification number equivalent. The compounded solubleoil had free alkalinity of about 0.09-0.10 percent as NaOH.

The soluble oil composition was tested for stability by allowing it tostand at F. for 48-72 hours and then observing the soluble oil at roomtemperature to determine whether any oil had separated from the solubleoil to form an upper oil layer, and whether there were any signs ofhaziness or gelation in the soluble oil. The soluble oil was rated asstable if there were no discernible oil separation, haziness, orgelation; otherwise, unstable.

The soluble oil was also tested for emulsion stability by emulsifying 10ml. of the soluble oil in 90 ml. of added 45 F. tap water having calciumhardness less than 100 p. p. m. as CaCOs, allowing the emulsion to cometo room temperature while standing for 24 hours at the end of which timethe appearance of the emulsion was observed to determine whether or notit was stable. If the emulsion surface was bright, or if it was onlyslightly dull, with very little or no cream on the surface, the emulsionwas rated stable. If there was a substantial amount of cream or scum orfree oil on the emulsion surface, the emulsion was rated unstable.

The synthetic soluble oil prepared as described above, containing n-amylalcohol as coupling agent was found to pass both the oil stability andthe emulsion stability tests as above described, thus showing that amylalcohol is a satisfactory coupling agent for synthetic soluble oils. Inthe absence of the coupling agent, the oil is unstable and the emulsionis rated unstable.

Example II Synthetic soluble oils were prepared and tested in the samemanner described in Example I except that iso-amyl alcohol(CH3)2CHCH2CH2OH, was used in place of the coupling agent employed inExample I. The following Example III.

4 I table shows the results obtained with various water contents and 2.0volume percent coupling agent content:

V01. Per- Vol. Percent cent Oil Stabil- Emulsion Water Coupling ityStability Agent 3. 0 2.0 Stable Stable. 3.5 2.0 do Do. 4.0 2.0 do Do.

This table shows that satisfactory results are obtained with watercontents of 3.0 to 4.0 volume percent and coupling agent content of 2.0volume percent.

Example III The synthetic soluble oil described in Example I, containingn-amyl alcohol as coupling agent, was tested for hard water emulsionstability by emulsifying 10 parts by volume of the soluble oil in partsby volume of 45 F. hard water containing 300 p. p. m. of calciumhardness as CaCOs and p. p. m. of chloride hardness as NaCl. Theresulting emulsion was allowed to come to room temperature whilestanding for 24 hours, at the end of which time the emulsion was ratedfor stability. If the emulsion surface was bright, or if there was onlyslight cream or scum on the surface the emulsion was rated stable. Ifthere was heavy cream or scum, or free oil on the smulsion surface, theemulsion was rated unstable. The tap water emulsions as prepared in thepreceding examples are rated somewhat more rigorously than the hardwater emulsions of the present example,

. since hard water emulsions generally tend to be less stable Vol. Per-Vol. Percent cent Oil Stabil- Emuls on Water Coupling ity StabilityAgent 'This table shows that satisfactory results are obtained in hardwater emulsion with synthetic soluble oils containing 2.8 to 3.8 volumepercent of water and 1.75 to 2.25 volume percent of n-amyl alcohol ascoupling agent.

Example IV The synthetic soluble oil described in Example II, containingiso-amyl alcohol as coupling agent, was tested for hard water emulsionstability in the manner described in The following results wereobtained.

This example shows that satisfactory results are obtained in hard wateremulsion with synthetic soluble oils containing 2.8 to 4.0 volumepercent of water and 1.75 to 2.25 volume percent of isoamyl alcohol ascoupling agent.

Comparison Example I Synthetic soluble oils were prepared and tested inthe same manner disclosed in Example I except that n-hexyl alcohol wasemployed in place of the coupling agent employed in Example I. Thefollowing results were obtained:

Vol. Per- Vol. Pee

cent cent Oil Stabil- Emulsion Water Coupling ity Stability Agent 2. 0.Unstable" Unstable 2.0 1.0 .do Do. 2.0 2.0 do.. Do. .50 0.5 do.... Do.6.0 1.0 d0 D0. 3.0 2. 0 Stable D0. 4.0 0.5 Unstable D0. 4.0 1.0 do Do.4.0 2.0 do Do.

This table shows that n-hexyl alcohol provides unsatisfactory emulsionstabilities even in ordinary tap water emulsions, whereas as shown inExample I and II, n-amyl alcohol and iso-amyl alcohol are capable ofproviding satisfactory emulsion stabilities in such emulsions.

Comparison Example 1] Synthetic soluble oils were prepared and testedfor hard water emulsion stability in the same manner described inExample 11 1 except that, in each of three different sets of runs, adifferent coupling agent was used in place of the coupling agentemployed in Example III. The three coupling agents were tertiary amylalcohol, (CH3)2C(OH)CH2CH3, n-butyl alcohol, CH3(CH2)3OH, and isopropylalcohol (CH3)2CHOH. Each coupling agent was tested with variouscombinations of coupling agent content and water content within theranges 2.8 to 3.8 volume percent water and 1.5 to 2.0 volume percentcoupling agent. In no case was a stable emulsion obtained. On the otherhand, as shown in Examples III and IV, normal amyl alcohol and isoamylalcohol give satisfactory emulsion stability ratings in hard wateremulsions.

The preferred water concentration varies for different coupling agentswithin the scope of the invention. For example, in the case of n-amylalcohol, the preferred water concentration in the particular solubleoils of the examples is within the range from 2.75 to 3.75 volumepercent whereas, in the case of isoamyl alcohol, the preferred waterconcentration in those soluble oils is 2.75 to 4.25 volume percent.

The properties of the oxidation product which is employed in syntheticsoluble oils aifects substantially the ease with which oil stability andemulsion stability can be imparted to the soluble oil by use of acoupling agent. The coupling agents according to the invention areparticularly advantageous in that they are capable of imparting oilstability and emulsion stability to synthetic soluble oils which containan oxidation product which makes the soluble oil relatively quitediflicult to stabilize.

The invention claimed is:

1. A soluble oil composition comprising: mineral lubricating oil; alkalimetal soap of petroleum mahogany sulfonic acids; alkali metal soap ofpetroleum naphthenic acids; at saponified oxidation product mixtureobtained by partially oxidizing petroleum foots oil in liquid phase at atemperature in the range from 260 to 320 F. and a pressure fromatmospheric to p. s. i. g. in the presence of a metallic oxidationcatalyst until the saponification number of the oxidation productmixture is within the range from 60 to mg. of KOH per gram, andsaponifying said oxidation product mixture with an alkali metal basiccompound; 1.75 to 3.0 volume percent of an alcohol consistingessentially of a primary amyl alcohol; and 2.75 to 5.0 volume percent ofwater; said soluble oil having sulfonate saponification equivalentwithin the range from 3 to 10 mg. of KOH per gram and carboxylatesaponification number equivalent Within the range from 10 to 20 mg. ofKOH per gram, said saponification product mixture providing carboxylatesaponification number equivalent within the approximate range from 5 to10 mg. of KOH per gram, and said alkali metal soap of petroleumnaphthenic acids providing carboxylate saponification number equivalentwithin the approximate range from 5 to 10 mg. of KOH per gram.

2. A soluble oil composition comprising: mineral lubrieating oil havingS. U. viscosity at 100 F. within the range from 40 to 120 seconds;alkali metal soap of petroleum mahogany sulfonic acids; alkali metalsoap of petroleum naphthenic acids; a saponified oxidation productmixture obtained by partially oxidizing petroleum foots oil in liquidphase at a temperature in the range from 260 F. to 320 F. and a pressurefrom atmospheric to 100 p. s. i. g. in the presence of a metallicoxidation catalyst until the saponification number of the oxidationproduet mixture is within the range from 60 to 120 mg. of KOH per gram,and saponifying said. oxidation product mixture with an alkali metalbasic compound; 2.75 to 5.0

volume percent of water; and 1.75 to 3.0 volume percent of a couplingagent consisting essentially of a primary amyl alcohol; said soluble oilhaving sulfonate saponification number equivalent within the approximaterange from 3 to 10 mg. of KOH per gram and carboxylate saponificationnumber equivalent within the approximate range from 10 to 20 mg. of KOHper gram, approximately half of said carboxylate saponification numberequivalent being supplied by said oxidation product mixture.

'3. Composition according to claim 1 wherein said alcohol is n-amylalcohol.

4. Composition according to claim 1 wherein said alcow hol is isoamylalcohol.

References Cited in the file of this patent UNITED STATES PATENTS2,006,557 Lenher July 2, 1935 2,043,922 Burwell June 9, 1936 2,265,799Carlson Dec. 9, 1941 2,470,913 Bjorksten May 24, 1949 2,668,146 CafcasFeb. 2, 1954 OTHER REFERENCES Metal Working Lubricants by Bastian,McGnaw-Hill Pub. Co., 1951, page 6.

1. A SOLUBLE OIL COMPOSITION COMPRISING: MINERAL LUBRICATING OIL; ALKALIMETAL SOAP OF PETROLEUM MAHOGANY SULFONIC ACIDS; ALKALI METAL SOAP OFPETROLEUM NAPHTHENIC ACIDS; A SAPONIFIED OXIDATION PRODUCT MIXTUREOBTAINED BY PARTIALLY OXIDIZING PETROLEUM FOOTS OIL IN LIQUID PHASE AT ATEMPERATURE IN THE RANGE FROM 260* TO 320* F. AND A PRESSURE FROMATMOSPHERIC TO 100 P. S. I. G. IN THE PRESENCE OF A METALLIC OXIDATIONCATALYST UNTIL THE SAPONIFICATION MEMBER OF THE OXIDATION PRODUCTMIXTURE IS WITHIN THE RANGE FROM 60 TO 120 MG. OF KOH PER GRAM, ANDSAPONIFYING SAID OXIDATION PRODUCT MIXTURE WITH AN ALKALI METAL BASICCOMPOUND; 1.75 TO 3.0 VOLUME PERCENT OF AN ALCOHOL CONSISTINGESSENTIALLY OF A PRIMARY AMYL ALCOHOL; AND 2.75 TO 5.0 VOLUME PERCENT OFWATER; SAID SOLUBLE OIL HAVING SULFONATE SAPONIFICATION EQUIVALENTWITHIN THE RANGE FROM 3 TO 10 MG. OF KOH PER GRAM AND CARBOXYLATESAPONIFICATION NUMBER EQUIVALENT WITHIN THE RANGE FROM 10 TO 20 MG. OFKOH PER GRAM, SAID SAPONIFICATION PRODUCT MIXTURE PROVIDING CARBOXYLATESAPONIFICATION NUMBR EQUIVALENT WITHIN THE APPROXIMATE RANGE FROM 5 TO10 MG. OF KOH PER GRAM, AND SAID ALKALI METAL SOAP OF PETROLEUMNAPHTHENIC ACIDS PROVIDING CARBOXYLATE SAPONIFICATION NUMBER EQUIVALENTWITHIN THE APPROXIMATE RANGE FROM 5 TO 10 MG. OF KOH PER GRAM.